A variety of communication standards are used to connect electronic devices to different electronic devices or peripheral devices in a wired configuration. In the communication standards, the shapes of connectors (plugs: inlet side) and sockets (receptacles: outlet side) are defined and compatibility with the conventional connectors and sockets is preferably maintained in upgrading the versions of the communication standards. USB (Universal Serial Bus) 3.0 is available as one example of standards defining the shapes of sockets in consideration of compatibility with USB 2.0 connectors and sockets.
Non-Patent Literature 1 (ITmedia Inc., “Windows Insider Glossary: USB 3.0 (Universal Serial Bus 3.0),” [online], Jun. 8, 2009, [Searched on Oct. 10, 2017], Internet URL: http://www.atmarkit.co.jp/ait/articles/0906/08/news109.ht ml) discloses the shapes of USB 3.0 standard Type-B (Standard-B) sockets. A USB 3.0 standard Type-B socket includes a protruding member including a USB 2.0 standard terminal for communication based on the USB 2.0 standard upon connection to a USB 2.0 standard connector, and a protruding member including a terminal added based on the USB 3.0 standard.